K0900E70 Datasheet, PDF (140/224 Pages) Teccor Electronics – Thyristor Product Catalog

AN1003
Application Notes
120 V ac
(High)
AC
(Return)
White
R1
47
RV₁
Varistor
150 W
Lamp
R₃
20 M
Remote
Switch
Connector
JP1
Dim
S₁
3
2
Bright
S₂
1
C₃
0.1 µF
R₂
1M
D1
1N4001
D1
1N4001
+5 V
U1
V_DD
VSS
GP₅
GP0
GP₄
GP₁
GP₃
GP₂
12C508
R₄
470
R5
470
VDD
D3
1N5231
C₁
220 µF
C2
0.01 µF
Q1
L4008L5
R6
470
Figure AN1003.23 Microcontroller Light Dimmer Control
With a zero crossing state detected, software can be written to
turn on the triac by going from tri-state to a logic high on the gate
and be synchronized with the AC phase cycles (Quadrants I
and IV). Using pull-down switches connected to the microcontol-
ler inputs, the user can signal the software to adjust the duty
cycle of the triac.
For higher amperage loads, a small 0.8 A, TO-92 triac (operating
in Quadrants I and IV) can be used to drive a 25 A alternistor
triac (operating in Quadrants I and III) as shown in the heater
control illustration in Figure AN1003.24.
For a complete listing of the software used to control this circuit,
see the Microchip application note PICREF-4. This application
note can be downloaded from Microchip's Web site at
www.microchip.com.
http://www.teccor.com
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AN1003 - 8
©2002 Teccor Electronics
Thyristor Product Catalog